The present invention relates to a vacuum processing apparatus and an ion pump, particularly, to a vacuum processing apparatus for performing, for example, a pattern depicting operation within a process chamber evacuated to a high vacuum by an ion pump like a charged beam pattern depicting apparatus and to an ion pump.
It was customary in the past to use a turbo molecular pump or an ion pump for producing a high vacuum. However, the turbo molecular pump is mechanically vibrated and, thus, cannot be used in the case where the vibration causes the accuracy of the depicted pattern to be lowered as in the charged beam pattern depicting apparatus. Therefore, in the charged beam pattern depicting apparatus, the pattern depicting chamber (process chamber) is evacuated to a high vacuum by the ion pump that is not vibrated at least during the pattern depiction.
However, as a result of an extensive research conducted in an attempt to further improve the accuracy of the pattern depiction in a charged beam pattern depicting apparatus, the present inventors have found that ions or electrons leak from the ion pump to enter the pattern depicting chamber (process chamber), with the result that these leaking ions or electrons chemically react with the resist on which a pattern is to be depicted so as to lower the accuracy of the pattern depiction.
An object of the present invention, which has been achieved on the basis of the finding noted above, is to provide a vacuum processing apparatus capable of suppressing deterioration of the processing caused by leakage of ions and electrons from the ion pump such as a lowered accuracy of the pattern depiction with a charged beam and to provide an ion pump.
According to a first aspect of the present invention, there is provided a vacuum processing apparatus for processing a target object within a process chamber evacuated to a high vacuum by an ion pump, comprising:
a conductor arranged in a vicinity of a suction port of a process chamber communicating with the ion pump, the conductor being electrically insulated from the process chamber; and
voltage applying means for imparting potential differing from that of the process chamber to the conductor.
The apparatus of the particular construction permits suppressing leakage of ions and electrons from the ion pump into the process chamber so as to suppress deterioration of the processing and, thus, to improve the accuracy of the pattern depiction.
The process chamber may consist of a pattern depicting chamber in which a pattern is depicted by a charged beam. Also, it is desirable for the voltage applying means to be constructed such that the applied voltage can be controlled depending on the pattern depicting conditions. It is also desirable for the voltage applying means to be constructed such that a positive (+) voltage is applied to the conductor for effectively suppressing the deterioration of the processing.
According to a second aspect of the present invention, there is provided an ion pump, comprising:
a conductor mounted within a suction port of the ion pump, the conductor being electrically insulated from the casing of the ion pump; and
voltage applying means for imparting potential differing from that of the casing to the conductor.
Where the conductor is mounted within the suction port of the ion port, it is possible to obtain the function and effect similar to those obtained in the case where the conductor is mounted to the process chamber as in the vacuum processing apparatus of the present invention.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.